1. In computer programming, to remove an element from the code and replace it with benign but useless data. A noun or pronoun can be used between "dummy" and "out." You can just write a script that fulfills each possible parameter, then dummy out the parameters that aren't necessary to the final build.
2. By extension, in video games, to remove an element of the game that was previously available. A noun or pronoun can be used between "dummy" and "out." They released a totally OP armor set in their last update, only to dummy it out in the next one.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.